How long do massive stars live?

Hint: How long a star lives depends upon how fast it uses up its nuclear fuel. The more it uses its fuel, the more it is likely to die soon.

Complete answer: Almost every star in the universe burns as a result of fusion of hydrogen and helium at its core where temperatures could be as high as 20 million degrees. In case of massive stars, the core is extremely hot and receives a lot of pressure from outer layers, more than other usual stars. These factors cause the energy generation to happen at a much faster rate. This means that these stars use up their fuel much before other stars.
On the other hand, stars which are not so massive, consume their energy much slower and can live upto 15 billion years. However, since these are not so massive and have less energy output, these would not look as bright and only look very faint to the naked eye.
Our sun, which can be classified as an average star in this regard has been existing for 5 billion years, and has fuel enough to last it another 5 billion years.

Note: Stars, on an average, have lived a few hundred million years and are gradually coming to their demise. However, massive stars such as the red Betelgeuse in Orion live much shorter lives. It could not have lived more than 10 million years and will last only a million years more or so.